Sustainability Reporting Practice Under the CSRD and ISSB Standards: Evidence From EU and UK Companies

Abstract

This thesis investigated how sustainability disclosure outcomes differ under the European Union’s Corporate Sustainability Reporting Directive (CSRD), which embeds double materiality, and the United Kingdom’s emerging ISSB-aligned framework based on enterprise-value-oriented single materiality. Despite extensive theoretical debate, empirical evidence comparing real-world reporting outputs under the two approaches remained limited. To address this gap, I analyzed sustainability disclosures from 24 multinational companies, using a matched-pairs sectoral design comparing 12 EU CSRD-aligned firms and 12 UK ISSB-aligned firms across six industries. Firms were matched by sector, relative market capitalization, international business footprint, and listing status to ensure comparability in scale, operational complexity, and exposure to global sustainability risks. A mixed-methods content analysis evaluated disclosure breadth, depth, narrative quality and comparability using 43 structured indicators across environmental, social, governance, materiality, and reporting-architecture dimensions. The analysis combined quantitative scoring—based on the presence, specificity, and metricization of disclosures—with qualitative assessment of narrative coherence, cross-referencing, and alignment between stated material topics and reported key performance indicators. A standardized coding framework was developed ex ante, and disclosures were systematically coded against predefined criteria to enhance consistency and replicability across the sample. Findings showed that CSRD-aligned reports provided broader and more impact-inclusive disclosure, particularly on biodiversity, nature-capital dependencies and Scope 1–3 emissions. UK reports were strong in climate and selected social impact domains, but presented greater variation in non-climate environmental metrics. While single materiality is often assumed to enhance comparability, the results indicate that structural comparability is currently higher under CSRD due to ESRS-driven standardization, KPI tabulation, definitional clarity and assurance requirements. The study demonstrated that materiality philosophy shapes reporting outcomes, but interacts with regulatory design, sector characteristics and organizational capability. I developed a hybrid generative-AI-assisted content-analysis approach, offering a scalable method for cross-jurisdictional ESG research. The findings contribute empirical evidence to ongoing debates around disclosure convergence, suggesting that global alignment will require harmonization of definitions and metrics—not only harmonization of materiality principles.